Don't try to create a symlink if the DATA DIRECTORY specified for a table

is the same as the normal datadir for that database. (Bug #8707)

mysql-test/r/symlink.result

@@ -84,3 +84,17 @@ t1	CREATE TABLE `t1` (
   `b` int(11) default NULL
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 drop table t1;
+create table t1 (i int) data directory = "/home/jimw/my/mysql-4.1-8707/mysql-test/var/master-data/test/";
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `i` int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;
+create table t1 (i int) index directory = "/home/jimw/my/mysql-4.1-8707/mysql-test/var/master-data/test/";
+show create table t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `i` int(11) default NULL
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+drop table t1;

mysql-test/t/symlink.test

@@ -115,3 +115,14 @@ eval alter table t1 index directory="$MYSQL_TEST_DIR/var/log";
 enable_query_log;
 show create table t1;
 drop table t1;
+
+#
+# Test specifying DATA DIRECTORY that is the same as what would normally
+# have been chosen. (Bug #8707)
+#
+eval create table t1 (i int) data directory = "$MYSQL_TEST_DIR/var/master-data/test/";
+show create table t1;
+drop table t1;
+eval create table t1 (i int) index directory = "$MYSQL_TEST_DIR/var/master-data/test/";
+show create table t1;
+drop table t1;

mysys/my_symlink2.c

@@ -32,6 +32,7 @@ File my_create_with_symlink(const char *linkname, const char *filename,
   int tmp_errno;
   /* Test if we should create a link */
   int create_link;
+  char abs_linkname[FN_REFLEN];
   DBUG_ENTER("my_create_with_symlink");
 
   if (my_disable_symlinks)
@@ -42,7 +43,11 @@ File my_create_with_symlink(const char *linkname, const char *filename,
       filename= linkname;
   }
   else
-    create_link= (linkname && strcmp(linkname,filename));    
+  {
+    if (linkname)
+      my_realpath(&abs_linkname, linkname, MYF(0));
+    create_link= (linkname && strcmp(abs_linkname,filename));
+  }
 
   if (!(MyFlags & MY_DELETE_OLD))
   {